Solutions of lactic acid salts of piperazinylquinolone- and piperazinyl-azaquinolone-carboxylic acids

ABSTRACT

The invention relates to solutions of piperazinylquinolone- and piperazinyl-azaquinolone-carboxylic acids, and in particular both ready-to-use injection and/or infusion solutions and dosage forms which can be converted into such injection and/or infusion solutions before use. The solutions according to the invention are characterized in that, besides the lactic acid salts of the active substance and, if appropriate, customary auxiliaries, they additonally contain at least one acid which does not lead to precipitates, in particular lactic acid.

This is a division of application Ser. No. 644,834, filed 8/27/84 (now U.S. Pat. No. 4,705,789).

The invention relates to solutions of piperazinylquinolone- and piperazinyl-azaquinolone-carboxylic acids, and in particular both ready-to-use injection and/or infusion solutions and dosage forms which can be converted into such injection and/or infusion solutions before use.

The solutions according to the invention are characterised in that, besides the lactic acid salts of the active substance and, if appropriate, customary auxiliaries, they additionally contain at least one acid which does not lead to precipitates, in particular lactic acid.

Possible active substances are at least one of the compounds of the formulae I or II ##STR1## in which X denotes N, C--H or C--F,

Z denotes O or CH₂,

R₁ denotes hydrogen methyl, ethyl or β-hydroxyethyl,

R₂ denotes cyclopropyl or ethyl and

R₃ denotes hydrogen, methyl or ethyl.

Compounds which may be mentioned in particular are: 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)quinoline-3-carboxylic acid (compound A); 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-quinoline-3-carboxylic acid (compound B); 9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid (compound C); 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid (compound D); and 1,cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(4-ethyl-1-piperazinyl)-quinoline-3-carboxylic acid (Compound E).

These substances are known to have powerful antibacterial action and are therefore suitable as medicaments for combating bacterial infections in warm-blooded animals.

The compounds of the formula I are known from: J. Med. Chem. 23 1958 (1980); DE-OS (German Published Specification) No. 3,142,854; DE-OS (German Published Specification) 3,033,157; and EP-OS (European Published Specification) No. 0,067,666.

The compounds of the formula II are known from: EP OS (European Published Specification) No. 0,047,005; DE-OS (German Published Specification) No. 3,037,103; and DE-OS (German Published Specification) No. 2,914,258.

Suitable customary auxiliaries for the solutions according to the invention are non-toxic, pharmaceutical carrier substances. These are, for example, thickeners, absorption accelerators, absorption inhibitors, crystallisation retarders, complexing agents, antioxidants, isotonicity agents or euhydrating agents. They can be solid, semi-solid or liquid in consistency.

Examples of possible acids which do not lead to precipitates are methanesulphonic acid, propionic acid, succinic acid, hydrochloric acid and, in particular, lactic acid.

For various reasons, acid addition salts or alkali metal salts of active compounds are frequently used in pharmacy. Addition salts of the active sustances can be prepared from several inorganic and organic acids, such as, for example, sulphuric acid, nitric acid, hydrochloric acid, citric acid, acetic acid, malic acid, succinic acid, tartaric acid, fumaric acid and methanesulphonic acid.

However, many such salts are unsuitable or very poorly suitable for the preparation of infusion and/or injection solutions, because, for example, the pH and/or the solubility and/or the shelf life, especially in respect of deposits, of the ready-to-use infusion and/or injection solution does not fulfill the pharmaceutical requirements to be imposed on such solutions.

It has now been found that the solutions can be stored if, besides the lactic acid salt of at least one of the active substances and, if appropriate, customary auxiliaries, they additionally contain at least one acid which does not lead to precipitates, in particular lactic acid.

The presence of such acids, in particular lactic acid, or, depending on the pH, a mixture of acid(s) and anion(s) thereof, is essential for the stability of the solution to be administered, in particular in respect to deposits.

Depending on the primary means of packaging used, the concentration of the active substance in the solution, the pH of the solution and the shelf-life requirements imposed, the content of excess lactic acid of the solutions according to the invention can be 0.01 to 90%. The lactic acid content of the solution to be administered can be 0.01 to 25% preferably 0.025 to 1.4%.

These quantity data relate to the total amount of excess acid, that is to say non-dissociated and dissociated acid.

Where these acids required for the stability are referred to below, in particular lactic acid, the total amount of excess acid is meant that is to say non-diisociated and dissociated acid.

If other acids which do not lead to precipitates are used, such as, for example, methanesulphonic acid, propionic acid, hydrochloric acid or succinic acid, the content of excess acid can be 0.05 to 4%, preferably between 0.3 and 2%, depending on the concentration of the active substance, the shelf-life requirements imposed and the pH of the ready-to-use solutions according to the invention.

The pH of the ready-to-use solutions according to the invention can be between 2.5 and 7, preferably between 3.5 and 4.5.

It was very surprising to discover that by addition of at least one acid which does not lead to precipitates, in particular lactic acid, in amounts such as those given above, it was also possible to stabilise infusion and/or injection solutions of the lactic acid salt of compound B, D and E, whilst the 1:1 stoichiometric salts of these compounds tended to give deposits. This also applies to the formulations, according to the invention, of compound C.

It has furthermore been found that there are several possible processes for the preparation of the solutions according to the invention.

The lactic acid salt of the active substance or a hydrate thereof can be used as the starting substance for the preparation of the solution of the active substance. In this case, it is possible to incorporate the required addition, or some of this addition, of at least one acid which does not lead to precipitates, in particular lactic acid, into the lactic acid salt, for example by freeze-drying.

However, the lactic acid salts can also be prepared directly in the solution, and in particular by addition of the amounts of lactic acid required for salt formation.

It is in this way possible to prepare both ready-to-use solutions of the active substance, filled in suitable containers, for example in ampoules or injection or infusion bottles, as well as precursors, for example concentrates or dry ampoules, suitable for the preparation of such solutions.

The solutions according to the invention, like the compounds of the formulae I and II on which they are based, are to be used as medicaments for combating bacterial infections. Possible uses are as injections and infusions. The dosages correspond to those of the known compounds A, B, C, D and E. Unless otherwise specified, all parts and/or percentages as used herein are parts or percentages by weight per unit volume.

Formulations

The solutions according to the invention are prepared by dissolving the active substance or the lactic acid salt thereof and, if appropriate, customary auxiliaries, in a solution of lactic acid or a mixture of lactic acid and, for example, sodium lactate, if necessary with slight warming.

If appropriate, water or a mixture of water and sodium hydroxide solution is also added to adjust the desired concentration of the active substance and/or the pH of the solution.

    ______________________________________                                         Example 1                                                                      1-Cyclopropyl-6-fluoro-1,4-dihydro-4-                                                                  -150 g                                                 oxo-7-(1-piperazinyl)-quinolone-3-                                             carboxylic acid (compound A)                                                   Lactic acid (90% by weight)                                                                            -262 g                                                 2 M sodium hydroxide solution                                                                          -266 g                                                 Water                   to 150 liters                                          Example 2                                                                      Monolactate of compound A                                                                              -1.27 g                                                Lactic acid (90% by weight)                                                                            -1.45 g                                                2 M sodium hydroxide solution                                                                          -1.80 g                                                Mannitol                -1.37 g                                                Water                   to 100.0 ml                                            Example 3                                                                      Compound A              -10.00 g                                               Lactic acid (90% by weight)                                                                            -4.85 g                                                Water                   to 1000.0 ml                                           Example 4                                                                      1-Ethyl-6-fluoro-1,4-dihydro-4-                                                                        -1.00 g                                                oxo-7-(1-piperazinyl)-quinoline-                                               3-carboxylic acid (compound B)                                                 Lactic acid (90% by weight)                                                                            -0.50 g                                                Glucose                 -3.85 g                                                Water                   to 100.00 ml                                           Example 5                                                                      9-Fluoro-3-methyl-10-(4-methyl-1-                                                                      -5.00 g                                                piperazinyl)-7-oxo-2,3-dihydro-7H--                                            pyrido-[1,2,3-de]-4-benzoxazine-6-                                             carboxylic acid (compound C)                                                   Lactic acid (90% by weight)                                                                            -2.20 g                                                Water                   to 100.00 ml                                           Example 6                                                                      Dihydrate of the monolactate of                                                                        -69.0 g                                                compound A                                                                     Lactic acid (90% by weight)                                                                            -24.2 g                                                Water                   to 1000.0 ml                                           Example 7                                                                      Compound A              -300.0 g                                               Lactic acid (90% by weight)                                                                            -177.3 g                                               Water                   to 6000.0 ml                                           Example 8                                                                      Compound A              -200.0 g                                               Lactic acid (90% by weight)                                                                            -75.0 g                                                Water                   to 2000.0 ml                                           Example 9                                                                      Monolactate of compound B                                                                              -128.2 g                                               Lactic acid (90% by weight)                                                                            -50.0 g                                                Water                   to 1000.0 ml                                           Example 10                                                                     Compound C              -100.0 g                                               Lactic acic (90% by weight)                                                                            -44.4 g                                                Water                   to 1000.0 ml                                           Example 11                                                                     Compound A              -30.0 g                                                Lactic acic (90% by weight)                                                                            to 100.0 g                                             Example 12                                                                     Compound A              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.30 g                                                 Succinic acid           0.71 g                                                 Water                   to 100.00 ml                                           Adusted to pH 3.6 with 2 M sodium hydroxide solution.                          Example 13                                                                     Monolactate of compound A                                                                              1.27 g                                                 Methanesulphonic acid   0.60 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.9 with 2 M sodium hydroxide solution.                         Example 14                                                                     Monolactate of compound A                                                                              1.27 g                                                 Lactic acid (90% by weight)                                                                            0.56 g                                                 Methanesulphonic acid   1.45 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.7 with 2 M sodium hydroxide solution.                         Example 15                                                                     Compound A              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.86 g                                                 Propionic acid          1.12 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.8 with 2 M sodium hydroxide solution.                         Example 16                                                                     Compound B              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.87 g                                                 Propionic acid          0.46 g                                                 Water                   to 100.00 ml                                           Example 17                                                                     Monolactate of compound B                                                                              1.28 g                                                 Lactic acid (90% by weight)                                                                            1.11 g                                                 Succinic acid           1.85 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.7 with 2 M sodium hydroxide solution.                         Example 18                                                                     Compound B              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.42 g                                                 Methanesulphonic acid   1.50 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.8 with 2 M sodium hydroxide solution.                         Example 19                                                                     Compound C              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.39 g                                                 Methanesulphonic acid   0.53 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.9 with 2 M sodium hydroxide solution.                         Example 20                                                                     Monolactate of compound C                                                                              1.25 g                                                 Lactic acid (90% by weight)                                                                            0.56 g                                                 Propionic acid          1.03 g                                                 Water                   to 100.00 ml                                           Example 21                                                                     Compound C              1.00 g                                                 Lactic acid (90% by weight)                                                                            1.39 g                                                 Succinic acid           0.64 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.7 with 2 M sodium hydroxide solution.                         Example 22                                                                     Compound A              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.33 g                                                 1 M hydrochloric acid   1.20 g                                                 Water                   to 100.00 ml                                           Example 23                                                                     Compound A              1.00 g                                                 Lactic acid (90% by weight)                                                                            0 41 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 4.0 with 1 M hydrochloric acid.                                 Example 24                                                                     Compound A              20.00 g                                                Lactic acid (90% by weight)                                                                            8.26 g                                                 Water                   to 100.00 ml                                           Adjusted to pH 3.6 with 1 M hydrochloric acid.                                 Example 25                                                                     Compound E              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.33 g                                                 Water                   to 100.00 ml                                           Example 26                                                                     Compound E              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.44 g                                                 Benzylalcohol           1.00 g                                                 Water                   to 100.00 ml                                           Example 27                                                                     Compound E              1.00 g                                                 Lactic acid (90% by weight)                                                                            0.33 g                                                 1 M hydrochloric acid   0.66 g                                                 Water                   to 100.00 ml                                           Example 28                                                                     Compound E              2.50 g                                                 Lactic acid (90% by weight)                                                                            0.83 g                                                 1 M hydrochloric acid   1.65 g                                                 Water                   to 100.00 ml                                           Example 29                                                                     Compound E              10.00 g                                                Lactic acid (90% by weight)                                                                            8.33 g                                                 Hydrochloric acid (25%) 1.30 g                                                 Water                   to 100.00 ml                                           Example 30                                                                     Compound E              5.00 g                                                 Lactic acid (90% by weight)                                                                            2.22 g                                                 Sodiummetabisulfite     0.20 g                                                 Water                   to 100.00 ml                                           ______________________________________                                     

What is claimed is:
 1. An aqueous storage stable solution which can be converted into an injection or diffusion solution consisting essentially of (a) a lactic acid salt of a piperazinylquinolonecarboxylic acid of the formula ##STR2## in which R₁ denotes hydrogen, methyl, ethyl or β-hydroxyethyl,R₃ denotes hydrogen, methyl or ethyl,and (b) and excess acid selected from the group consisting of methanesulphonic acid, propionic acid, succinic acid, hydrochloric acid and lactic acid in an amount which does not lead to precipitates and constituting about 0.01 to 90% based on the solution.
 2. A solution according to claim 1, wherein the excess acid is present in about 0.01 to 25%.
 3. A solution according to claim 1, wherein the excess acid is present in the solution in a concentration of from 0.025 to 1.4%. 